Photographic silver halide elements of the Lippmann-type

ABSTRACT

WHEREIN: R is hydrogen, acyl, haloacyl or acyl carrying a quaternary ammonium group, R1 is an aliphatic, aromatic or heterocyclic group, and R2 is hydrogen, the group -S-R1 or one or more substituents selected from alkyl, aryl, halogen, hydroxyl or alkoxy. The compounds reduce distortions of image-details, enhance image-sharpness and reduce yellowing upon reversal processing.   Lippmann-emulsions are described which comprise a compound of the formula:

United States Patent [191 Philippaerts et al.

11] 3,869,290 Mar. 4, 1975 PHOTOGRAPHIC SILVER HALIDE ELEMENTS OF THE LIPPMANN-TYPE [22] Filed: Nov. 3, 1972 [2]] Appl. No.: 303,403

[30} Foreign Application Priority Data Nov. 10, l97l Great Britain 52289/71 {52] U.S. Cl. 96/76 R, 96/67, 96/84 R,

96/94 R [51] Int. Cl. G03c l/fgfl [58] Field of Search 96/94 R, 95, 76 R, 84 R [56] References Cited UNITED STATES PATENTS 3,379,529 4/l968 Porter et al 96/36.2 3,705,038 l2/l972 Philippaerts et al. 96/140 Primary Examinew-Norman G. Torchin Assistant ExaminerAlfonso T. Suro Pico Attorney, Agent, or Firm-A. W. Breiner ABSTRACT Lippmann-emulsions are described which comprise a compound of the formula:

wherein:

R is hydrogen, acyl, haloacyl or acyl carrying a quaternary ammonium group,

R is an aliphatic, aromatic or heterocyclic group,

and

R is hydrogen, the group ,SR or one or more substituents selected from alkyl, aryl, halogen, hydroxyl or alkoxy;

The compounds reduce distortions of image-details, enhance image-sharpness and reduce yellowing upon reversal processing.

5 Claims, No Drawings PHOTOGRAPHIC SILVER HALIDE ELEMENTS OF THE LIPPMANNTYPE For instance, in the production of microelectronic 1 integrated circuits, drawings are made on highly enlarged scale of the various successive masks necessary to produce one integrated circuit whereupon the drawings are reduced, if necessary in successive steps, and reproduced on a photographic plate or film material forming thereby the mask ready for use. By various photographic and chemical steps (photo-etching of lacquered plates) the images of the masks thus produced are transferred to the surface on which the integrated circuit is to be made, in order to produce the required circuit elements.

The photographic materials for use in the production of masks as described above should have a high resolving power and acutance, and allow a correct reproduction of the dimensions of the image. However, with 30 fluence of closely adjacent image details and the image sharpness does not always meet the requirements.

It has now been found that the above disadvantageous effects can be reduced or eliminated by incorpo' rating in the Lippmann-emulsions hydroquinone derivatives corresponding to the following general formula wherein R stands for hydrogen, acyl e.g,. acetyl, halcacyl e.g. haloacetyl or acyl carrying a quaternary ammo nium group,

R stands for an aliphatic group, more particularly alkyl including substituted alkyl e.g. alkyl substituted with carboxy, with aryl or with a heterocycle, an'aromatic group more particularly aryl including substituted aryl e.g. aryl substituted with halogen or 'with C,C alkyl, or preferably a heterocyclic group, e.g. a l-substituted S-tetrazolyl group and a Z-benzothiazolyl group, and

R represents hydrogen, the group -SR, or one or more of the known substituents used in hydroqui none-type developing'agents e.g. alkyl, aryl, halogen, hydroxyl, alkoxy, etc.

Representative examples of compounds corresponding to the above general formula are listed below. They can be prepared as described in the literature referred to or in the preparations hereinafter.

J.Org;.Chem. 2 9 59 9 Jbrgchem. 23, 59s (1964) J..Org.Chem.. Q, 598 (19 l l s- 7. OCGH Cl a. i H

-s-(c11 -cr1 As is illustrated in the preparations hereinafter and as Preparation 1 1 Compound 4 To a solution of 16.4 g (0.1 mole) of 2-mercaptomethylbenzimidazole in 200 ml of methanol, a solution of 12.2 g (0.1 mole) of toluquinone in 150 ml of methanol was added at once at room temperature with stirring. After minutes, the reaction mixture was concentrated by evaporation and the residue was recrystallized from nitromethane. Yield 11.5 g (40 7a Melting point 120C.

Preparation 2 Compound 5 To a suspension of 83.5 g (05 mole) of 2-mercaptobenzothiazole in 750 ml of methanol, 54 g (0.5 mole) of p-benzoquinone were added portion-wise at a temperature below 10C and with stirring. First a solution was formed and then the product crystallized.

J.Chem.Eng. Data 2, 252-8 British Patent '1 ,058,606

U.S.-Patent 5,045,690

The precipitate was purified by dissolution in 800 ml of boiling ethylene glycol monomethyl ether and precipitation by means of 1600 ml of water. Yield 98 g (71 7a). Melting point 205C.

Preparation 3 Compound 8 To a solution of 54 g (0.5 mole) of p-benzoquinone in 800 m1 of methanol, 129 g (0.5 mole) of n-hexadecylmercaptan were added at once at room temperature and with stirring. The temperature rose to maximum 45C. The mixture was left standing overnight and then poured into 5 litres of water. The precipitate was purified by continuous extraction with methanol followed by recrystallization from n-hexane. Yield 75 g (41 7(). Melting point 8890C.

Both in reversal and negative processing of Lippmann-emulsions the use of the compounds corresponding to the above formula results in an enhancement of the image sharpness, particularly sharpness of fine detail, and in a favourable effect on the distortion of image-details. In addition thereto, where reversal processing of Lippmann material is very critical and often gives rise to yellow staining, probably owing to residual oxidation products of the developing agent. it was found that the compounds used according to the invention counteract said yellowing.

The compounds for use in accordance with the present invention are incorporated in the emulsion layer by addition, as a solution or dispersion, to the coating compositions of the Lippmann emulsion.

The concentration of the compounds used according to the invention depends on the characteristics of both the chosen compound and the emulsion and is therefore best determined by trial. In most cases the optimum concentration in the silver halide emulsion is between about 20 mg and about 2 g, preferably between about 100 mg and 1 g per mole of silver halide.

The thickness of the emulsion layer of a photographic material according to the present invention is generally comprised between about 3 microns and about 8 microns, and the average grain size of the silver halide grains is generally less than 80 nm. The ratio of silver halide to hydrophilic colloid binder in the Lipp' mann emulsion according to the present invention is preferably at least 1:2 and at most 4:1.

The silver halide Lippmann emulsions may be prepared according to methods well known in the art and described in the literature (see e.g. P. Glafkids Photographic Chemistry", .Vol. 1, 1958, pages 365-368, Mees/James The theory of the Photographic Process", 1966, p. 36 and National Physical Laboratory Notes on Applied Science no. 20 Small Scale preparation of fine-grain (colloidal) Photographic emulsions, B. H. Crawford, London, 1960). They may also be prepared according to the technique described in co-pending United Kingdom Pat. Application No. 15,948/70.

Silver halide Lippmann-emulsions with very fine grain can be obtained by effecting the precipitation of the silver halide in the presence of heterocyclic mercapto compounds as described in United Kingdom Pat. Specification No. 1,204,623 or in the presence of compounds as described in co-pending United Kingdom Pats. Nos. 1,320,138 and 1,318,518.

The hydrophilic colloid used as the vehicle for the silver halide may be any of the common hydrophilic colloids employed in photographic light-sensitive emulsions for example, gelatin, albumin, zein, casein, alginic acid, a cellulose derivative such as carboxymethyl cellulose, a synthetic hydrophilic colloid such as polyvinyl alcohol and poly-N-vinyl pyrrolidone, etc. If desired compatible mixtures of two or more colloids may be employed for dispersing the silver halide.

Various silver salts may be used as the light-sensitive salt such as silver bromide, silver iodide, silver chloride, or mixed silver halides such as silver chlorobromide, silver bromoiodide and silver chlorobromoiodide. Silver bromide emulsions which may have a iodide content of at most 8 mole /1 and having an average grainsize of at most 80 nm are favoured.

The emulsions may be coated on a wide variety of photographic emulsion supports. Typical supports include cellulose ester film, polyvinyl acetal film, polystyrene film, polyethylene terephthalate film and related films of resinous material as well as paper and glass. In the manufacture of high-resolution plate materials for the preparation of masks for use in the electronic industry, glass supports are most advantageously used in view of their high dimensional stability.

The light-sensitive silver halide emulsions of use in the preparation of a photographic material according to the present invention may be chemically as well as spectrally sensitized.

They may be spectrally sensitized by any of the known spectral sensitizers such as cyanines and mero- 6 cyanine dyes for photographic light-sensitive silver halide materials. The silver halide emulsions for microelectronic mask making according to the present invention are most advantageously sensitized for the green 5 region of the spectrum. The exposure light is preferably chosen so that it radiates light of a. wavelength to which the emulsion has been spectrally sensitized.

They may be chemically sensitized by effecting the ripening in the presence of small amounts of sulphur containing compounds such as allyl thiocyanate. allyl thiourea, sodium thiosulphate, etc. The emulsions may also be sensitized by means of reductors for instance tin compounds as described in French Pat. Specification No. 1,146,955 and in Belgian Pat. Specification No. 568,687, imino-amino methane sulphinic acid compounds as described in United Kingdom Pat. Specification No. 789,823 and small amounts of noble metal compounds such as gold, platinum, palladium, iridium, ruthenium and rhodium.

The said emulsions may also comprise compounds which sensitize the emulsion by development acceleration for example compounds of the polyoxyalkylene type such as alkylene oxide condensation products as described among other in US. Pats. Nos. 2,531,832

and 2,533,990, in United Kingdom Pat. Specifications Nos. 920,637, 940,051, 945,340 and 991,608 and in Belgian Pat. Specification No. 648,710 and the known onium compounds including quaternary ammonium, quaternary phosphonium and ternary sulphonium compounds as well as onium derivatives of amino-N-oxides as described in United Kingdom P'at. Specification No.

Further the emulsions may comprise stabilizers e.g. heterocyclic nitrogen-containing thioxo compounds such as benzothiazoline-Z-thione and l-phenyl-2-tetrazoline-S-thiohe and compounds of the hydroxytriazolopyrimidine type. They can also be stabilized with mercury compounds such as the mercury compounds described in Belgian Pat. Specifications Nos. 524,121 and 677,337, United Kingdom Pat. Specification No. 1,173,609 and in US. Pat. No. 3,179,520.

The emulsions may also comprise light-absorbing dyes which are so chosen that they absorb light of the wavelength to which the material is exposed so that scattering and reflection of light within the photographic material is reduced. For more details regarding these dyes there can be referred to Belgian Pat. Specification No. 699,375 and co-pending United Kingdom Pat. No. 1,298,335. The dyes are preferably used in such amounts that per micron of emulsion layer thickness a density comprised between 0.05 and 0.20, measured in the spectral region of the exposure light, is obtained.

Any of the hardening agents for hydrophilic colloids may be used in the emulsions according to the present invention such as chromium, aluminium, and zirconium salts, formaldehyde, dialdehydes, hydroxy aldehydes, acrolein, glyoxal, halogen substituted aldehyde acids such as mucochloric acid and mucobromic acid, diketones such as divinyl ketone, compounds carrying one or more vinylsulphonyl groups such as divinylsulphone, l,3,5-trivinylsulphonylbenzene, hexahydro-striazines carrying vin ylcarbonyl, halogenoacetyl and/or acyl groups such as l,3,5-triacryloylhexahydro l,3,5- triazine, 1,3-diacryloyl-5-acetylhexahydro-l ,3 ,5- triazine, 1,3,5-trichloroacetylhexahydro-1,3,5-tria2ine, etc.

In order to promote adhesion ofthe emulsion to glass supports in the preparation ofhigh resolution plate materials, the silicon compounds described in co-pending United Kingdom Pat. No. l,286,467 can be incorporated into the emulsion.

The light-sensitive emulsions may also comprise all other kinds of ingredients such as plasticizers, coating aids, etc.

Though the invention has been particularly described in view of the preparation of masks as used in the production of microelectronic integrated circuits, the compounds described have the same favourable effects in Lippmann-materials used for other purposes where high-resolution and high acutance is of primary impor- 'tance.

The following examples illustrate the present invention.

Example 1 A silver bromide emulsion comprising per kg 72 g of silver bromide and 93 g of gelatin was prepared by simultaneous addition of a silver nitrate solution and a potassium bromide solution to a 3 7c aqueous solution of gelatin. The conditions of precipitation were adjusted so that a Lippmann emulsion with an average grain size of 70 nm was obtained. Details as to the preparation of Lippmann emulsions can be found amongst others in P. Glafkids Photographic Chemistry", Vol. I, 1958, Fountain Press, London.

The emulsion was sensitized by addition of 150 mg per 100 g of silver halide of a merocyanine dye by means of which a strong spectral sensitization in the region of 520-550 mp. was obtained. Then, an amount of the light-absorbing dye having the following structural formula t It Hooe-l: --C=CH-CH= cH-li c-cooH was added so as to obtain, after the emulsion is coated, a density of 0.10 per micron of emulsion layer thickness, measured at 550 mp. (absorption maximum of the light-absorbing dye used).

The emulsion was divided into 4 portions and to each portion, except for one, one ofthe compounds 1,4 and 5 respectively was added in an amount of 500 mg per mole of silver halide.

The emulsion portions were coated on glass plates pro rata of 230 ml per sq.m so as to obtain after drying a layer thickness of 6 ,u. The 4 plate materials A, B. C and D were then exposed under identical circumstances by means of monochromatic light, the spectral composition of which corresponds with the absorption region of the light-absorbing dye used, through a test pattern, as normally used for the quantitative evaluation of materials for use in microelectronics maskmaking, consisting of lines which are separated by spaces of the same width as the lines themselves and with a width varying from 1 to 20 ,u.. The exposure was of such an intensity so as to limit the density in the transparent areas of the images produced, which correspond with the white lines of the test pattern, to the fog value.

After the exposure the 4 plate materials were reversal processedat 20C, under completely identical circumstances.

For that purpose the exposed materials were first developed for about 5 min. in the following developing liquid the pH of which was adjusted to l05 hydroquinone monomethyl-p-aminophenyl hemisulphate potassium bromide sodium carbonate sodium sulphite potassium thiocyanate water to make The materials were then treated for about 5 min. in

the following bleach bath potassium dichromate 5 g strong sulphuric acid (d 1.85) l() ccs water to make i000 ccs.

After rinsing for some minutes in water the materials were treated for 5 minutes in a clearing bath of the following composition sodium sulphite I000 ccs water to make After rinsing again for some minutes the materials were subjected to an overall exposure in order to render the residual silver bromide developable whereupon they were treated for about 6 minutes in the following developing liquid hydroquinone monomethyl-p-aminophenol hemisulphate sodium sulphite sodium carbonate potassium bromide water to make EXAMPLE 2 Example 1 was repeated with the difference that materials A to D were processed so as to obtain a negative image by means of a developing liquid of the following composition water 800 ml monomethyl-p-aminophcnol hemisulphate l.5 g sodium sulphIte (anhydrous) 25 g hydroquinone 6 g sodium carbonate (anhydrous) 40 g potassium bromide l g water to make 1 itre.

As compared with material A, materials B, C and D showed improved image-sharpness and less distortions in line-reproduction.

We claim:

1. Photographic silver halide emulsion including a silver halide and hydrophilic colloid binder, said emulsion being of the Lippmann type having an average grain size of less than 100 nm and comprising from 20 mg to 2 g per mole of silver halide of a compound of the formula:

stituents selected from alkyl, aryl, halogen, hydroxyl and alkoxy; the ratio of silver halide to hydrophilic colloid binder in the emulsion being from 1 2 and 4 l.

2. Photographic emulsion according to claim 1, wherein in the formula R, stands for l'substituted 5- tetrazolyl or for Z-benzothiazolyl and both R nd R are hydrogen.

3. Photographic emulsion according to claim I. wherein the said emulsion is a silver bromide emulsion which may have a silver iodide content of at most 8 mole 7c and having an average grain-size of at most 4. Photographic material comprising a support and an emulsion as defined in claim 1.

5. Photographic material according to claim 4, wherein the support is a glass sup-port. 

1. PHOTOGRAPHIC SILVER HALIDE EMULSION INCLUDING A SILVER HALIDE AND HYDROPHILIC COLLOID BINDER, SAID EMULSION BEING OF THE LIPPMAN TYPE HAVING AN AVERGAGE GRAIN SIZE OF LESS THAN 100 MM AND COMPRISING FROM 20 MG TO 2 G PER MOLE OF SILVER HALIDE OF A COMPOUND OF THE FORMULA:
 2. Photographic emulsion according to claim 1, wherein in the formula R1 stands for 1-substituted 5-tetrazolyl or for 2-benzothiazolyl and both R nd R2 are hydrogen.
 3. Photographic emulsion according to claim 1, wherein the said emulsion is a silver bromide emulsion which may have a silver iodide content of at most 8 mole % and having an average grain-size of at most 80 nm.
 4. Photographic material comprising a support and an emulsion as defined in claim
 1. 5. Photographic material according to claim 4, wherein the support is a glass support. 